1. Field of the Invention
The present invention relates to a liquid crystal lens and a manufacturing method thereof, more specifically to a liquid crystal lens and a manufacturing method thereof that can focus rapidly by applying a small voltage.
2. Description of Related Art
A liquid crystal lens is an optical device that can focus or diverge the light by utilizing the characteristics of a birefringence of liquid crystal molecules and an alignment of liquid crystal molecules with a distribution of an electric field. In order to achieve the result of zoom, a conventional optical zoom lens should include at least two lenses with moving toward or away with each other. Disadvantages of this are that the weight of the overall optical configuration is heavy and its volume is large. The liquid crystal lens can change the focus length by changing the working voltage, and light and thin are the best advantages of the liquid crystal lens so that it is capable of optical zoom in a small space. However, the worst disadvantage is that the thicker thickness of the crystal liquid will cause the reaction time longer. For example, if the thickness of the crystal liquid layer is 60 micrometer, the reaction time of the liquid crystal layer is about 30 seconds and the need of the working voltage is over 30 volt voltage. Due to this, it is quite not convenient for the user in practical applications.
In order to solve the foregoing problems, U.S. Pat. No. 4,190,330 discloses a variable focus liquid crystal lens system, which can change the direction of the crystal liquid by changing the electric field or magnetic field after the liquid crystal material is packaged so that the focal length of the lens system changes from a first focal length to a second focal length. Further, U.S. Pat. No. 4,572,616 discloses another kind of variable focus liquid crystal lens system, which uses special electrodes and electric field to control the direction of the liquid crystal so that different refractions are obtained and the light can be focused. Besides, U.S. Pat. No. 5,150,234 discloses a pickup-lens module, which disposes the liquid crystal lens units into the pickup-lens module so that it's effect to change the focus length, it can reduce the volume of the pickup-lens module, and it's easy to manufacture.
However, longer reaction time and higher working voltage of the problems of the crystal liquid lens still can't be solved effectively in the foregoing patents of the prior art. Therefore, it is very urgent and important to provide a crystal liquid lens that has low working voltage and rapid reaction time.